One prior arrangement for providing a selectable format scans the maximum total screen area utilized by the combined formats and displays characters only in the desired portions of the cathode ray tube screen. Such an arrangement results in unnecessary power dissipation since the entire screen of the CRT is scanned while only a portion is utilized. Further, since the maximum screen area is scanned, some of the display time is unused resulting in a reduction in the overall information throughput efficiency. Still another prior arrangement physically rotates the cathode ray tube yoke structure ninety degrees by means of a mechanical coupling thus providing two alternate formats. A major drawback to this configuration is that the yoke positioning mechanism is large and expensive particularly if reasonable positional accuracy is desired. Some commercial products obtain format selection by using linear deflection amplifiers capable of producing a desired display format in either of two orientations. As a result of the voltages utilized and power controlled, the circuitry involved is large and expensive and therefore not economically competitive. The hereinafter described apparatus obtains alternate display format selection by changing the frequency of the horizontal sweep signal so as to produce a change in the number of lines during each raster and changes the amplitude of the vertical sweep signal to correspond to the change in the number of lines in the CRT raster.